Electrically operated fuse



Aug. 24, 1954 E. J. NAUMANN 2,537,095

ELECTRICALLY OPERATED FUSE Filed June 4, 1945 5 Sheets-Sheet l WITNESSES? I l I INVENTOR @XM w Edward J flay/770x20. fbwPa ilvm ATTORNEY 1954 E. J. NAUMANN 2,687,095

ELECTRICALLY OPERATED FUSE Filed June 4, 1945 3 Sheets-Sheet 2 WITNESSES: INVENTOR fJM [ah era (IA 000240.

GM/P a ATTORNEY Patented Aug. 24, 1954 ELECTRICALLY OPERATED FUSE Edward J. Naumann, Baltimore, Md., assignor, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Application June 4, 1945, Serial No. 597,571

6 Claims.

This invention relates generally to ordnance devices and more particularly to ordnance fuses of the type which may be adjusted to respond to the proximity of a target over a predetermined range of distances therefrom.

Proximity fuses are applied to various types of bombs, shells, torpedoes, etc., and usually have a small very compact radio transmitter built into the fuse which is generally attached to the nose of the projectile. The operation of this radio unit in most cases depends upon the Doppler effect, but sometimes the result is obtained by photoelectric circuits or other means of electrical discharge or response when the fuse equipped projectile approaches its target.

With all such electrically operated proximity fuses, an electrical power supply is required to energize the various electrical components of the electronic system. In most of these systems, in addition to various low voltage power supply sources, a high-voltage plate supply for the tubes is required, usually of the order of, say, 150 volts. Heretofore small batteries have furnished the required electrical power. These batteries have many disadvantages. In almost all fuses the space is limited and it is essential that the power supply for these fuses occupy as little space as possible. For the most part, such batteries are bulky and must be made up in special cases to conform to certain design requirements. The power produced with respect to the size of the batteries must be very large and as a consequence high efficiency batteries are needed. These have a relatively short life when stored. After a short storage period their power may drop to such a low level as to render them useless in a proximity fuse. Batteries are further objectionable in that they are not dependable when exposed to low temperatures. Still further, with such battery power supplies there is a constant danger that the fuse might be exploded inadvertently due to a short circuit or for some other reason resulting in an electrical discharge into the heater, which ignites the squib, for the reason that the batteries throughout their life when once connected in the fuse circuits ofier an ever present source of electrical energy.

Thus this invention has for one of its important objects the provision of a proximity type of ordnance fuse which is entirely reliable in its operation.

Another object of this invention is to provide an ordnance fuse of the character mentioned in which inadvertent application of the power supply to the circuit elements of the .fuse is minimized.

Another object of this invention is to provide an ordnance fuse of the type described in which deterioration of the power supply therefor with time is practically negligible.

A specific object of this invention is to utilize a small generator as the source of power in a proximity fuse, which generator, for example, may be driven by a suitable fluid operated device.

In certain applications where a generator or an alternator is used to supply current to the electrical apparatus of a proximity fuse of a projectile, it is not feasible to use a fluid operated device, such as an externally mounted propeller driven by the relative wind. This is particularly true in certain rocket type projectiles which operate at extremely high speeds.

Thi invention also contemplates a drive for operating certain elements of a proximity fuse which is independent of the motion of the projectile with respect to the surrounding fluid medium.

More specifically stated this invention has for another of its objects the provision of a selfcontained drive for operating certain elements of an ordnance fuse.

Other objects and advantages will becom apparent upon a study of the following specification when considered in conjunction with the accompanying drawings in which:

Figure 1 is a perspective view illustrating one type of proximity fuse;

Fig. 2 is an elevational view partly in section showing some details of the ordnance fuse of Fig. 1;

Fig. 3 is a plan view of a generator embodied in thi invention;

Fig. 4 is a plan view of a modified form of the generator of Fig. 3;

Fig. 5 is a diagram showing how the windings of the generator of Fig. 4 may be connected;

Fig. 6 is a diagram showing another method of connecting the windings of the generator of Fig. 4;

Fig. 7 illustrates a type of permanent magnet rotor which may be employed in the generators of Fig. 3 and Fig. 4;

Fig. 8 illustrates a type of direct-current generator which may be embodied in the present invention;

Fig. 9 is a detail showing of a fluid pressure supply element and its control mechanism.

Fig. 10 is a sectional view taken on the line X--X of Fig. 9;

Fig. 11 is a sectional view showing a selfcontained fluid operated drive for an ordnance fuse which operates independently of the motion of the fuse equipped projectile with respect to the relative wind.

Fig. 12 is a view, partly in section, looking into the front end of the fuse of Fig. 11 with the front housing removed;

Fig. 13 is a schematic diagram of a type of power supply for an ordnance fuse which involves only a low-voltage battery in the system; and

Fig. la is a block diagram of the electrical elements of a Doppler operated fuse according to this invention.

A fuse of the type which depends for its op eration upon the Doppler effect is illustrated in Fig. 1 of the drawings. Systems for the operation of such electronic fuses sometimes consist of a radiating heterodyne detector coupled to an amplifier and trigger circuit. An arrangement of this type is shown in the block diagram of Fig. 14. The antennae radiate energy to the target which, in turn, reflects the radiated energy back to the fuse. Ihe reflected signal which is received mixes with the direct signal from the oscillator as in a heterodyne receiver. The reflected signal frequency is dependent upon the velocity of the fuse with respect to the target as well as the frequency of the direct signal. The Doppler frequency equations relate the direct signal frequency to the reflected signal frequency if the velocity between the signal source and the observer, or in this case the receiver, is considered equal to twice the relative velocity of the fuse and the target. This condition substantially obtains, because of the relative motion between the receiver in the fuse and the target and, therefore, the reflected signal in most cases differs in frequency from the direct signal. The reflected wave upon being mixed with the direct signal in the heterodyne circuits produces a beat frequency signal. This beat signal increases in amplitude as the fuse approaches the target; it is amplified in the amplifier which is responsive only to the limited range of Doppler frequencies and then passed to the trigger circuit where'it is utilized to trigger, for example, a thyratron tube, which, when the beat signal amplitude is sufficient, becomes conducting and passes current through a heater. This heater ignites a squib which forms part of a powder train for igniting the main powder charge of the bomb. Electrical energy for operating the fuse elements is derived from the permanent magnet generator 6.

The electronic elements of the proximity fuse are carried in the forward extremities I and 2 (see Fig. 1) of the fuse and are connected to the dipoles or antennae 3 from which the direct signals are transmitted and by which the reflected signals are received. Batteries for supplying the required electric power to the electronic elements were, in the past, housed in the fuse section designated 4. The bomb was armed by a switch controlled by the plunger 33 operating in conjunction with a resistor capacitor circuit controlled by a thyratron tube which in turn was triggered by the antenna signal.

This invention in the embodiment represented in Figs. 1 and Z obviates the many disadvantages of battery energized weapons by providing a generator designated 6 in place of the batteries and operating such generator together with other arming features of the fuse directly from the propeller 5. As shown in thevgenerator plan view of Fig. 3 this generator comprises a permanent magnet rotor I having six alternately magnetized pole teeth and three U-shaped stator sections 8 displaced by Each U- shaped stator section straddles a pair of alternately magnetized rotor poles. About each pole leg of the stator section has two assembly 9 is disposed, thus each stator section has two coil assemblies and the generator or alternator a total of six. The large coils 9a are the high voltage coils and the small coils 9b are the low voltage coils. The high voltage coils may be connected in either series or parallel circuit relation depending upon the requirements to provide the plate supply voltage for the electronic system and the low voltage coils may be connected in suitable circuit relation to provide the low voltage system requirements such as the filament voltages. If a single coil is used on each pole leg, the generator output leads may be connected across an impedance element such as an autotransformer or a resistor and suitable taps taken therefrom to provide the system voltage requirements. Rectification of the output of the generator is common in most applications but where the frequency conditions permit separate rectification may be dispensed with.

The stator sections and rotor of the generator 6 are assembled between a pair of spaced circular plates II and I2 (see Fig. 2) of which II is largest. These plates are spaced a predetermined distance apart by means of the spacers l3 which are drilled and tapped at their eX- tremities to threadedly receive the screws [4 which join the circular plates to the spacers. Sleeves I5 space the stator sections between the plates and through bolts I6 secure the assembly. Sleeves H (see Fig. 3) about the generator rotor shaft :8 position the rotor in the plane of the stator. Suitable bearings IS) in the circular plates journal the rotor shaft. Power for driving the generator 6 is provided by the propeller 5 which tightly threadedly engages the extremity of the extension 2d of the generator shaft 58. The generator is securely clamped in the fuse with its plate H disposed between an outwardly flanged portion 2! of the fuse housing section 2 and a ring 22 which threadedly engages the internally threaded 1ocking ring 23 which is flanged inwardly to engage the outwardly flanged portion 2| of the housing section 2. The housing section ll also threadedly engages the locking ring 23 and threads therein to a sufficient depth to abut the ring 22. The other extremity of the housing section 4 is threaded internally to receive the end plate 24 having an integral externally threaded cylindrical section. 25 which threads into the nose of the projectile 26.

The generator shaft l8 extends through the bearing I 9 in the circular plate l2 and has mounted thereon a toothed wheel 21. The shaft extension beyond this toothed wheel drives a gear mechanism enclosed in the gear housing 28. Preferably, such gear mechanism provides a fairly large reduction in shaft speed between the input end and its output end and provides suitable translational motion to move the bridging contact 29, which may be of the form of a disc of material of good electrical conductivity insulated from the gear mechanism, to the left as viewed in Fig. 2 to bridge the contact members 30. In this position the contact 29 together with its carrier reaches a final contact closed posi tion at which time the carrier disengages the gear mesh and holds the contacts closed. Such details are not shown since the gear and contact mechanism per se forms no part of this invention. The contact members 30 are adapted for connection in the arming circuits of the electronic system of the fuse and when bridged by the disc 29 connect such system to the detonator or squib. The principle here is no different than that illustrated schematically in Fig. 14.

In order to prevent unwanted rotative movements of the generator the toothed wheel 21 is prevented from rotating bymeans of a safety device 3|. This safety device includes a member 32 having a hexagonal external configuration similar to a conventional nut, one extremity of which is reduced in size and threaded to thread -into the housing 4 directly over the toothed wheel, The member 32 is drilled and counterbored to receive a plunger 33 which plunger extends therethrough and engages the toothed wheel 2'1 between the teeth thereof. A spring 34 biases the plunger in a direction to cause ejection thereof from the member 32, such movement being prevented by the restraining or safety wire 35 extending transversely of the member 32 through holes provided therein and against which wire the outer extremity of the plunger 34 bears.

In addition to or as an alternative to the safety device just described a wire such as 3511 may pass through an eye provided on the ring 23 and thence through a hole drilled in the propeller blade. Beyond the blade a snap on attachment may be applied to the wire or a small disc as b which frictionally engages the wire may be provided. The disc pulls off the wire when the wire is jerked to the right as viewed in Figs. 1 and 2.

In the case of a bomb carrying a fuse, such as that described, when the bomb is loaded on an aircraft, an arming wire having one extremity secured to the airframe would be inserted through another pair of holes provided in the member 32. Thereafter the safety wire 35 is removed. When the dropping mechanism of the aircraft is operated and the bomb drops, the arming wire is jerked from the member 32, the plunger 33 is ejected and when suitable fluid pressure is applied to the blades of the propeller 5 to overcome the magnetic pull and friction drag of the generator and gear unit, rotation of the generator and operation of the circuit arming mechanism occurs. After a predetermined number of revolutions of the propeller the circuit arming contacts 30 are bridged by the movable contact 2! thus allowing the bomb to fall a safe distance away from the aircraft before the electronic control becomes active with respect to the detonator. The bomb is exploded by the electronic system, as before explained, when it reaches a predetermined distance from the target.

If it is necessary to jettison a load of bombs,

equipped with fuses according to this invention,

over friendly territory, the arming wires are dropped with the bombs. This prevents the propeller 5 from turning and consequently each bomb falls as a dud.

A propeller such as 5 may be made either of a metallic or a non-metallic material. Insofar as Doppler operated fuses are concerned, it has been found desirable to make the propellers of some form of plastic material to avoid the possibility of the induction of an artificial or extraneous signal which might cause detonation. This is not to be construed that a metal propeller may not be used, since, proper disposition of the dipoles or antenna 3 with respect to the propeller, or shielding, may be had to obviate propeller interference. Still further, if made of metal, the propeller may be used as the radiating antenna for the fuse.

Generators or alternators of the type described I in connection with Fig. 3 are operated at fairly high speeds. The speed range may be from 12,000 to 60,000 R. P. M. Thus the frequency of the electrical output of the alternator is quite high and it is a fairly simple matter in a small filtering circuit, for example, of the resistance input resistance-capacitance type to properly filter and thereafter rectify the alternating current so that it is adaptable for application to the electronic system of the fuse. Even after filtering and. rectification, however, a slight ripple voltage may yet remain having a frequency range close to the beat signal produced by the Doppler effect. As a consequence care must be exercised in designing the equipment that the beat signal frequency and the generator operating frequencies are sufficiently different that the generator frequencies may not detonate the bombs. This is aided in the instant case by a shaped amplifier which passes only the signals in the Doppler frequency range. However, an amplifier is not essential, since, any suitable filter is satisfactory in most cases.

In line with the foregoing consideration, if it is found that for a specific application the generator frequencies are not sufficiently high, then a generator or alternator, as indicated in Fig. 4, may be utilized. Here four U-shaped stator sections 8 spaced 90 mechanical degrees apart are utilized with a 6-hole permanent magnet motor I. The pole faces of these stator sections are disposed about the rotor and each pole leg carries a coil assembly 9. This mechanical arrangement of the magnetic system basically forms a twoephase alternator and it may be utilized as such. However, since high frequency is desired, it is preferred that the various winding groups be Scott or T- connected to product a three-phase output. These connections may be made either internally as in Fig. 5 or externally as in Fig. 6. For the connections indicated in Fig. 5 the large main windings 91a on the top and bottom stator sections are connected in series circuit relation. Similarly the main windings 9a on the left and right stator sections as viewed in Fig. 4 are connected in series circuit relation. This last-mentioned series circuit has one terminal thereof connected to the midpoint of the winding group on the top and bottom stator sections. The remaining three winding terminals are brought out and connected to a three-phase full wave rectifier iii. If it is essential, in a particular application, that the voltages of each of the three phases are equal, then the windings on the left and right stator sections may be so proportioned that their output is 86.6% of the voltage output of the windings on the top and bottom stator sections. On the other hand it may be more convenient to provide iden tical windings throughout and tap 86.8% of the winding voltage of the left andright stator sections or alternatively introduce a voltage dropping resistor into the circuit, all such expedients being well known. The rectifier output after suitable filtering is applied to the electronic system of the fuse.

In Fig. 6 the main windings 9a, on the top and bottom stator sections are again connected in series and the similar windings on the left and right stator sections of Fig. 4 are again in series. The terminals of each series circuit are connected across a primary P of a Scott connected trans- 7 former 38. The three terminals of the secondary winding S are connected to a three-phase full wave rectifier 31.

As a consequence of the foregoing arrangements, a multi-phase ripple voltage is produced. By this means a high-ripple frequency is produced which is easily filtered and which is generally far removed from the Doppler frequency. Thus danger of premature detonation from this source is eliminated. The output of the rectifiers 37 may be divided in any suitable manner to provide the necessary voltages for energizing the electronic system. Alternatively, additional windings as shown ma be provided and separately connected to provide a separate output either single phase or multi-phase. For example, the

filament circuits may be supplied by additional.

windings such as 922 connected to provide any of, single phase, two phase or three phase power and further supplying various tubes with various phase relationships if desired.

The rectifier units may be built up of small copper oxide or selenium units. However, almost any type of rectifiers may be used.

Toothed rotors of the type illustrated in Figs. 3 and 4 are not essential to good performance. For extremely high-speed operation a rotor, having a smooth periphery, which as illustrated in Fig. 7 is spot magnetized for six alternate magnetic poles. may be utilized. The structural strength advantages are self-evident. Further the windage losses at the rotor result only from skin friction which is negligible. As a consequence the available power at the propeller is more emciently utilized.

Such a rotor, by way of example, may be made of a magnetic combination of aluminum, nickel, cobalt and iron. It is spot magnetized by placing six equally distributed coil carrying poles thereabout and applying a heavy surge of unidirectional current to the coils. Another method which substantially increases the degree of magnetization applies the magnetic field to the rotor during the process of molding thereof. Once the rotor has cooled and all machining operations thereon are completed, the magnetic field is again applied in the same direction. The magnetic retentivity of rotors of the type described is high and deterioration with time, insofar as most applications are concerned, is practically negligible.

A type of direct-current generator which has been employed with good results is illustrated schematically in Fig. 8. This generator is selfexcited and consists of a single stator and. a single rotor. A commutator is mounted at each end of the rotor-these are designated 38 and 33. Separate armature windings (it! and ll are provided on the rotor. These may be wound together or separately in any suitable manner and the separate winding terminals connected to the respective commutators. A single shunt connected field winding 62 is employed. The winding arrangement on the stator and rotor is such that a highvoltage plate supply and a low-ilament-voltage output of the generator is provided for energizing the electronic system, of the fuse. When a direct current generator is employed as the energy source of the fuse the alternator and rectifiers can be dispensed with.

Certain types of projectiles, such as rockets, operate at speeds well above acoustic velocities. On these a propeller drive for the generator, as illustrated in Figs. 1 and 2, is not very satisfactory since the propeller efiiciency at speeds beyond the speed of sound in air drops rapidly.

This is occasioned by the break down in smooth airflow resulting in a high energy loss in air turbulence. Further the structural strength of a propeller projected into such a high velocity air stream must be great. t has also been found. that externally mounted propellers cause the projectile so equipped to deviate from the path of a standard or contact type of projectile thus making sighting by available methods difficult. Problems of this character are obviated and the performance of the proximity fuse measurably improved by providing a self-contained turbine drive of the character illustrated in Figs. 9 through 12. The type of fuse illustrated in these figures is a modification of that disclosed in the preceding figures of the drawing and certain of the inventive features thereof are described in the copending applications of R. N. Harman and E. J. Nauman, Serial Nos. 597,572 and 597,573, filed on the same date as this application, respectively entitled Drive Devices and Generators, and assigned to the same assignee as this invention.

In the type of fuss illustrated the turbine housing 45 and. the threaded cylindrical section 46, which threads into the nose of the projectile 26, is preferably die-cast as a single unit. A turbine 37 is suitably journalled in the housing 45 and is directly connected to a generator ll shown only in dotted outline, mounted within the cylindrical section at. The turbine drive continues through the generator to a gear reduction unit 48 beyond which the drive terminates in an arming switch within the casing 59 shown in dotted outline within the housing 5 l The housing as also contains the squib 52 ignited by the heater 53 and a highly explosive powder charge 5 5 ignited by the squib and generally known as the tetrobooster, which ignites the main powder charge of the projectile.

The electronic head 55 of the proximity fuse is molded as a separate section from the turbine housing t5 and is preferably of some material, such as a high strength plastic having good electrical insulating properties. It is provided with various openings and recesses (not shown) for housing the various electrical components of the electronic system as well as a recess for receiving a small capsule 56 of highl compressed gas. A tubular member 5? provides communication between the capsule 56 and the turbine input passageway 58 (see Fig. 12). The electronic head 55 forms a closure for the forward end of the turbine housing, thus sealing the turbine in its housing. The high-pressure gas is admitted substantially tangentially of the turbine passage against the turbine blades 59 and its flow is counterclockwise to the exhaust port 69. Rotation of the turbine is prevented by means of a spring biased plunger 33 similar in principle to that described in connection with Figs. 1 and 2, which operates in a suitably formed section of the turbine housing 65. The lower extremity of the plunger 33 engages the turbine blades and thus limits rotational movements of the turbine to the circumferential distance between the turbine blades. A suitable arming wire 6i which is attached to the rocked launching mechanism releases the plunger 33 as the rocket leaves the launching mechanism whereupon the plunger is ejected by the spring 34.

Application of the high-pressure gas to the turbine may be controlled by means of a valve mechanism such as illustrated in Figs. 9 and 10. The capsule 5B is sealed by a thin metal membrance 62 secured across the capsule opening by means of a valve mechanism 63 which threads onto the end of the capsule and engages the metal membrane or diaphragm 62. A small pointed spear or plunger 64 is slidably mounted in the valve with the point thereof directed towards the diaphragm. Beyond that portion of the Valve body which slidably carries the plunger 64, the valve body is counterbored to receive a second plunger 85. This second plunger 65 slides in a'casing 66 threadedly secured to the valve body and is spring biased in the direction of the pointed plunger 64 by a heavy compression spring 61 which is placed under high compression by means of the screw down cap 68. The plunger 85 is restrained in its latched position shown by the catch element 69 which engages the extremity of the plunger 65 to one side of the longitudinal axis thereof sufiicient to clear the stem of the spear or pointed plunger 64. An arming wire is attached to the catch element 69. Thus it is jerked from its plunger engaging position when the projectile is launched. This action is substantially simultaneous with the release of the turbine restraining plunger 33, causing the spear to puncture the diaphragm 62. Thus the gas under pressure is admitted to the passage which communicates with the tube 57 leading to the turbine passage. It should be noted that the gas supply need not be great. In the first place the turbine ordinarily need be operated only a few seconds and secondly the turbine is a fairly small device requiring little gas volume for operation.

It is possible to provide a power supply for a proximity fuse employing a battery as the energizing source, which has a fairly long life. This is shown in Fig. 13 wherein a battery H of fairly low voltage forms the energizing source. The battery voltage or any suitable portion thereof is utilized as the filament supply for the electronic system while the plate voltage is obtained from a parallel circuit across the battery including the propeller operated vibrator 14 and the step-up transformer 15. The contacts of the vibrator are mounted at the extremities of the spring conductors '56 which are cam actuated to closed and open position by mean of the cam TI on the propeller shaft. This produces a pulsating current in the primary of the voltage step-up transformer E5. The secondary output after suitable filtering and rectification forms the plate voltage supply for the electronic system. A suitable arming switch including the elements 29 and 3!! and the propeller driven gear reduction unit 28, as described in connection with Fig. 2, connects the battery 13 to the system after a predetermined number of propeller revolutions.

The foregoing disclosure and the showings made in the drawings are merely illustrative of the principles of this invention and are not to be considered in a limiting sense; the only limitations are to be determined from the scope of the appended claims.

I claim as my invention:

1. A control system for an ordinance fuse comprising, in combination, an assembly of dipoles, a radiating heterodyne detector circuit connected to said dipoles to energize said dipoles, said radiating heterodyne detector circuit producing an electrical output in dependence of the difference in frequency of transmitted and received signals on said dipoles, an amplifier responsive to a limited range of frequencies of output voltage of said radiating heterodyne detector, a detonating circuit for said fuse, a control circuit responsive to a predetermined magnitude of output voltage of said amplifier for energizing said detonating circuit, an alternating current generator, rectifier and filter circuit means for rectifying and filtering the output of said generator and energizing said radiating heterodyne detector, said amplifier and said control circuit, turbine means connected to said generator to drive said generator, and means for supplying a fluid under pressure to said turbine means to effect rotation thereof.

2. A control system for an ordinance fuse comprising, in combination, an assembly of dipoles, a radiating heterodyne detector circuit connected to said dipoles to energize said dipoles, said radiating heterodyne detector circuit producing an electrical output in dependence of the difference in frequency of transmitted and received signals on said dipoles, an amplifier responsive to a limited range of frequencies of output voltage of said radiating heterodyne detector, a detonating circuit for said fuse, a control circuit responsive to a predetermined magnitude of output voltage of said amplifier for energizing said detonating circuit, an alternating current generator having a high voltage output winding and a low voltage output winding, a rectifier and filter circuit for rectifying and filtering the output of said high voltage winding, said radiating heterodyne detector circuit, said amplifier and said control circuit each requiring a supply of high voltage direct current and low voltage alternating current, circuit mean connecting said rectifier and filter circuit and said low voltage output winding to each of said radiating heterodyne detector circuit, said amplifier and, said detonating circuit to effect energization thereof, turbine means connected to said generator to drive said generator, and means for supplying a fluid under pressure to said turbine means to effect rotation thereof.

3. Apparatus as set forth in claim 2 in which said last-named means comprises a container of high pressure gas, means forming a passage com municating with said container and saidturbine and control means for releasing said high pressure gas into said passage.

4 A control system for an ordinance fuse comprising, in combination, an assembly of dipoles, a radiating heterodyne detector circuit connected to said dipoles to energize said dipoles, said radiating heterodyne detector circuit producing an electrical output in dependence of the difference in frequency of transmitted and received signals on said dipoles, an amplifier responsive to a limited range of frequencies of output voltage of said radiating heterodyne detector, a detonating circuit for said fuse, a control circuit responsive to a predetermined magnitude of output voltage of said amplifier for energizing said detonating circuit, a battery, a transformer having a primary winding and a secondary winding, contact means connecting said primary winding across said battery, a fluid operated device for rapidly closing and opening said contact means to apply pulses of energy to said primary winding, means for applying a stream of fluid to said fluid operated device, and circuit means connecting said secondary winding to said radiating heterodyne detector, said amplifier and said control circuit.

5. A control system for an ordinance fuse comprising, in combination, an assembly of dipoles, a radiating heterodyne detector circuit connected to said dipoles to energize said dipoles, said radiating heterodyne detector circuit producing an electrical output in dependence 11 of the difierence in frequency of transmitted and received signals on said dipoles, an amplifier responsive to a limited range of frequencies of output voltage of said radiating heterodyne detector, a detonating circuit for said fuse, a control circuit responsive to a predetermined magnitude of output voltage of said amplifier for energizing said detonating circuit, power supply means for energizing said radiating heterodyne detector, said amplifier and said con- 1 trol circuit, and a fluid operated device for operating said power supply means.

6. Apparatus as set forth in claim 5 in which said power supply means comprises a generator having a permanent magnet rotor and means connecting said fluid operated device to drive said rotor.

References Cited in the file of this patent UNITED STATES PATENTS Number 1,318,954 1 1,957,016 2,137,598 1 2,178,047 2,255,245 0 2,278,247 2,377,174 2,403,567

Number 15 1,089 304,254 865,507

Name Date Barlow Oct. 14, 1919 Loudon May 1, 1934 Vos Nov. 22, 1938 Malme Oct. 31, 1939 Ferrel Sept. 9, 1941 Cullin Mar. 31, 1942 Parker May 29, 1945 Wales July 9, 1946 FOREIGN PATENTS Country Date Great Britain Jan. 13, 1912 Germany Oct. 1, 1920 France Feb. 24, 1941 

